Filter device

ABSTRACT

A filter device having two flow paths. The first flow path having at least one cap and fluid port. The second flow path surrounding the first fluid flow path and having at least one cap that overlaps the cap of the first fluid flow path. The second flow path also having at least one fluid port. The filter device providing a simple arrangement that is easily disinfected or sterilized.

FIELD OF THE INVENTION

[0001] The invention relates to a filter device having two flow spaces,of which a first space, preferably a permeate space, is formed by thetubular or capillary tube passages of a hollow-fiber bundle poured atits ends into a molding compound, and a second space, preferably afiltrate space, is formed by a housing enclosing the fiber bundle, thefirst space being sealed off by caps, placed on the molding compounds,with sealing devices running over the peripheral areas of said moldingcompounds, and the molding compounds being braced against the housing.

BACKGROUND OF THE INVENTION

[0002] The German laid open print 26 46 358 discloses a filter device inwhich the hollow-fiber bundle encloses a central conduit in a ring-likemanner, and the ends of the ring-shaped hollow-fiber bundle are sealedoff by a molding compound both with respect to the central conduit andwith respect to the housing casing concentrically enclosing it.

[0003] Another known filter device likewise comprises a tubular housingwhich encloses the hollow-fiber bundle, the ends of the hollow-fiberbundle being joined to the ends of the tubular housing by a moldingcompound. In this filter device, the housing is provided in each casewith radial connection pieces, adjacent to the molding compounds, whichform the inlets and outlets to the second flow space. The capillarytubes of the hollow-fiber bundle enclosed by the molding compounds arecut at their end faces to open them. Caps provided with connectionpieces which form the inlets and outlets of the first flow space arethen placed sealingly on the ends of the tubular casing.

[0004] These known filter devices are used, for example, as capillarydialyzers, the flow spaces formed by the capillary-tube passages formingthe blood chamber, and the housing enclosing the hollow-fiber bundleforming the dialysate chamber in which the dialysate flows around thehollow fibers.

[0005] The problem existing in the known filter devices is that themolding compound, usually made of PU [polyurethane fiber], which hardensin a disk shape and forms a sealing between the two flow spaces, shrinkswhen hardening, so that stresses develop in the disk-shaped sealingsformed by the molding compounds which can lead to cracks and evendetachments of the molding compounds from the housing casing enclosingthem. As a result, the two flow spaces are no longer completely sealedoff from one another, and the adhesion of the sealing compounds to thehousing enclosing the fiber bundle, said adhesion producing the seal, isno longer reliably assured.

[0006] In a filter device of the type indicated at the outset disclosedby EP 0 305 687 B1, the disk-shaped molding compounds are enclosed byinterposed rings to which the molding compounds do not adhere, so thatthey can shrink free of stress. This stress-free shrinking preventscracks in the disk-shaped molding compounds, and makes it possible todispense with a direct sealing between the peripheral edge of thesealing compounds and the housing enclosing them. To neverthelessmaintain a sealing between the two flow spaces, the first space issealed off by caps placed on the molding compound, and specifically bysealing devices which run over the edge area of the molding compound andagainst which the caps are pressed.

[0007] In this known filter device, the problem now exists of producinga connection to the second space formed by the housing enclosing thefiber bundle. This connection is produced in the known filter device, inthat the diameter of the tubular housing is widened at its end areasmore or less in the manner of a sleeve, these widened areas beingprovided with radial connection pieces. These connection pieces openthrough into the second space formed by the housing, the widenedsections of the housing being sealed off from the first space becausethe caps are sealingly joined to the widened sections, so that a sealingis produced to the outside by the cap edge, and a sealing is producedwith respect to the first space by the circumferential sealing ring.This type of arrangement of the connection pieces at the second spaceformed by the housing is relatively costly. Furthermore, dead spaceswhich are poorly rinsed develop above or below the connection pieces, atwhich gas bubbles can collect. This can have a disadvantageous effectduring disinfecting or sterilization, as well as generally whenhandling.

OBJECTS AND SUMMARY OF THE INVENTION

[0008] Therefore, the object of the invention is to produce a filterdevice of the type specified at the outset in which, on one hand, it isreliably assured that the two flow spaces are sealed off from oneanother by the hardened molding compounds, and on the other hand, asimple arrangement of the connection pieces for the second flow space isproduced and poorly rinsed dead spaces are moreover avoided.

[0009] This objective is achieved according to the invention, given afilter device having two flow spaces, the first space formed by tubularor capillary tube passages of a hollow-fiber bundle, said fiber bundlebeing poured at its ends into a molding compound, and a second spaceformed by the housing surrounding the fiber bundle. The inventionfurther entails the first space being sealed off by caps, placed on themolding compounds, with sealing devices being placed over the peripheralareas of the molding compounds, and the molding compounds being bracedagainst the housing. The molding compounds are hardened in moldsenclosing them at their end faces and peripheral sides to form disks.Caps are provided for the ends of the first space that seal to themolding compound and have a connection piece providing inflow/outflowaccess to the first space. A second set of caps, overlapping the firstcaps, is provided, said caps having a connection piece providinginflow/outflow access to the second space. The edges of the second capsbeing joined to the housing in a fluid tight manner, so that between thefirst and second set of caps, interspaces are formed, said interspacesbeing connected to the second space.

[0010] In the filter device according to the invention, the moldingcompounds are hardened in molds enclosing them on the face and at theirsides, so that the molding compounds are able to shrink free of stress.As in the known filter device, the sealing between the disk-shapedmolding compounds thus formed and the first caps is effected by insertedsealing means. However, to produce a simple access to the second flowspace, the corresponding connection pieces are no longer arranged on thehousing itself, but on the second cap overlapping the first cap. Thissimplifies the filter device.

[0011] The inner edges of the second caps overlapping the moldingcompounds advantageously extend beyond the molding compounds to theinside, so that a flow space is produced between the circumferentialwall of the second caps and the molding compounds or the fiber bundlesenclosed by them.

[0012] According to a preferred specific embodiment, thepipe-section-shaped housing, into which the hollow-fiber bundle isdrawn, is provided at the ends of its casing with tooth-like orscalloped projections formed by axial notches or indentations runningout freely, the outer areas of the projections being integrated into themolding compounds, so that the free inner areas of the notches orindentations form flow passages for the fluid. Since the housing, whichis pipe-section-shaped or preferably provided with a circularcross-section, is made of a material having elastic properties such asPC (polycarbonate), wreath-shaped edges made of flexible tongues areformed by the notches or indentations, said edges being at leastpartially enclosed by the molding compound. When the molding compoundthen hardens to form the disks, they can shrink essentially free ofstress, because the flexible tongues offer no significant resistance tothis shrinking. According to this refinement of the present invention,the disks formed by the molding compounds are firmly joined to the endsof the tubular housing, so that the two flow chambers can then bereliably separated from one another by the two caps overlapping oneanother, with the appropriate sealing means.

[0013] It may be that the filter device known from EP 0 305 387 B1 has atubular housing, in which wreath-shaped edges formed by notches orindentations are produced in the widened end sections and are partiallyenclosed by the molding compounds hardened to form disks. However, thesewreath-shaped edges made of rectangular projections demand a complicateddesign of the housing, because in addition, they are still enclosed bythe widened end sections of the housing which are provided with theconnection pieces.

[0014] The housing is expediently provided in the area of the inner endsof the projections with radial flanges, on which the edges of the secondcaps are sealingly supported, or to which they are secured.

[0015] Advantageously, the distance of the projections from one anotherin the circumferential direction is greater than their width.

[0016] According to one inventive embodiment, for which independentprotection is claimed, the cross-sectional area of the regions of thenotches or indentations free of the molding compounds is so dimensionedthat, starting from a radial connection piece, they increase in theircross-section, so that essentially equal partial quantities of the fluidcan enter and exit through the cross-sections. This embodiment takesinto account the circumstance that, in the annular space surrounding thefiber bundle and into which the liquid is fed through a radialconnection piece, a pressure drop occurs in the circumferentialdirection starting from the mouth of the connection piece. Adjusting thecross-sections of the intake ports to this pressure drop assures thatessentially equal quantities of fluid enter the openings distributedover the circumference.

[0017] A special problem in filter devices of the type indicated at theoutset is assuring that in the second space, the surfaces of the fibersin the hollow-fiber bundle are circumflowed as completely and uniformlyas possible by the introduced fluid, in order to increase theeffectiveness of the filter device. Therefore, according to oneparticularly preferred specific embodiment of the invention, insertedinto the housing are saucer-shaped rings whose legs are joined to theinside wall of the housing and which are provided with bore holes, andthat the inside wall is provided with bore holes opening through intothe annular spaces formed by the rings. An annular space is formed bythe saucer-shaped ring, in which the introduced fluid can spread outwell. The bore holes can be distributed uniformly over the periphery, indoing which the cross-sections of the bore holes can be adapted to thepressure drop occurring in the introduced fluid if it is fed into theannular space only through one bore hole or one radial connection piece.

[0018] To maintain an essentially uniform fluid pressure given aone-sided introduction of the fluid into the annular space, the boreholes and openings respectively having identical flow-throughcross-sections can be distributed with appropriately variable clearancesover the periphery of the inside wall of the annular space.

[0019] Advantageously, the rings have a U-shaped cross-section, the boreholes being arranged in the radial legs of the rings.

[0020] In the known filter device, the annular spaces formed by theannular grooves have an axial clearance with respect to the end disksformed by the molding compounds. Because of this, in the case of avertically standing filter device, for example, air bubbles can collectat the upper disk formed by the molding compound. Furthermore, airbubbles can also collect in the lower annular groove between the mouthof the radial connection piece and the groove bottom. A result of thisundesired collecting of air or air bubbles is that, for example, duringsterilization or disinfection of the filter, the air-filled areas do notcome in contact, or come only insufficiently in contact with thesterilizing or disinfecting means.

[0021] To achieve a complete deaeration of the hollow-fiber space, afurther inventive development provides that the annular spaces or thepassages connecting the annular spaces to the second space are joineddirectly to the molding compounds, or extend in the axial direction totheir area.

[0022] This refinement of the present invention prevents dead spacesbetween the connection pieces and the annular spaces respectively intowhich they discharge, so that no air can accumulate in unwanted mannerin dead spaces, and a complete circumcirculation of the hollow-fiberbundle by the fluid between the molding compounds is assured.

[0023] Expediently, both sides of the filter are identically shaped, sothat the effects provided according to the invention are attainable inany position of the filter.

[0024] The embodiment of the filter according to the invention also hasa favorable effect on the discharge side of the second space, since thefluid is withdrawn from the second space essentially uniformlydistributed over the annular space.

[0025] A further advantage of the present device is that its housing canbe made of a material such as propylene which does not form a tightadhesive bond with the molding compound. Therefore, it is possible toproduce the filter device according to the invention from less costlyplastic materials, which increases its economic efficiency.

[0026] A further inventive refinement relates to a filter device havingtwo flow spaces, of which a first space, preferably a permeate space, isformed by the tubular or capillary tube passages of a hollow-fiberbundle poured at its ends into a molding compound, and a second space,preferably a filtrate space, is formed by a housing enclosing thehollow-fiber bundle. The filtrate space is sealed off from the inletsand outlets of the tubes of the hollow-fiber bundle by the moldingcompound. Furthermore, at least two connection pieces are provided forthe feeding and removal of fluids into or out of each of the two spaces,of which at least one connection piece of the second space opens throughinto an annular space formed between the housing and the area of one endof the hollow-fiber bundle. To assure that there is no dead space in theannular space in which air bubbles can collect, the present inventionprovides that in the position of normal use, at least one annular spaceis located at the top, and that the annular space extends to the supplyline and discharge line respectively. Preferably dialysate can be fed orremoved through the upper annular space.

[0027] In the following, an exemplary embodiment of the invention isexplained in more detail with the aid of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028]FIG. 1 shows a longitudinal cross-section through one side of afilter device according to the invention,

[0029] FIGS. 2 to 4 show top views onto one end face of a disk formed bythe molding compound,

[0030]FIG. 5 shows a longitudinal cross-section through the housing of aknown filter device,

[0031]FIG. 6 shows a section through the upper area of the housing of afilter device according to the invention with closed annular space

[0032]FIG. 7 shows a side view of a filter device according to theinvention and

[0033]FIG. 8 shows a section through the filter device according to FIG.7;

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0034] Filter device 1 is made of a pipe-section-shaped housing 2 ofplastic such as PC, whose edges merge into a radial, annular flange 3.Joined to the housing, to the inner edge area of this flange 3 or to thetransition region between the cylindrical pipe section and the flange,is a cylindrical ring which is provided with indentations 5 that formrectangular notches which run out freely. Formed between these notches 5are scallop-like or tongue-like projections 4 which are likewiseessentially rectangular and extend in the axial direction. At theirupper, outer, end areas, these projections 4 have projections 6 pointingradially outwardly.

[0035] A hollow-fiber bundle 55 is introduced into pipe-shaped housing2. The ends of this hollow-fiber bundle are embedded in a moldingcompound 7 made, for example, of PU, which is disk-shaped afterhardening. Since during its hardening, the molding compound iscentrifuged about an axis of rotation at right angles to housing axis 8,disk 7 in the top view evident from FIG. 1 has a cylindricalsaucer-shaped inner side 9. The hardening is carried out in a cap whichrotates along and which delimits the end face and the peripheral side.The tolerance range within which cylindrical, saucer-shaped, inner side9 can move is indicated by broken lines 9′ and 9″.

[0036] After hardening the molding compound, disk 7 is cut at its endface 10, thus opening the small capillary tubes of the hollow-fiberbundle embedded in the molding compound.

[0037] A first cap 11, having a central connection piece 12 is thenplaced on end face 10 of disk 7, said cap being sealed off at its edgearea, by means of an O-ring 13, from the edge area of disk 7 free ofhollow fibers.

[0038] First cap 11 is enclosed by a second cap 14 having a cylindricalwall 15 whose edge area is joined in a fluid-tight manner to the outeredge of annular flange 3. Second cap 14 possesses a central, cylindricalextension prolongation 16 which forms a connection piece andconcentrically encloses the double-walled connection piece 12 of firstcap 11. Second cap 14 is provided on its inner side with ray-shaped webs17 which assure the necessary clearance to first cap 11, and thus defineflow channels. Cylindrical extension prolongation 16 is also provided onits inner side with radial webs 19 which are supported on the outercasing of connection piece 12 and define flow channels.

[0039] Radial webs 20, arranged in a star shape and used as stiffening,are provided on the lower side of first cap 11.

[0040] With its cylindrical edge 15, second cap 14 encloses, with radialclearance, disk 7 and scalloped or tooth-shaped extension prolongations4, thus forming an annular space 21 through which the fluid, introducedthrough connection piece 16, can enter through the inner areas of ports5 into the flow space enclosing the hollow-fiber bundle.

[0041] As FIGS. 2 to 4 show, the tooth-like or scallop-like projections4 and gaps 5 formed between them can have different lengths and formdifferent angles at circumference. The nose-shaped, radial projections 6can also vary in length and width.

[0042]FIG. 5 shows a longitudinal cross-section through the housing of aknown dialyzer. In this known dialyzer, the ends of hollow-fiber bundle25 are enclosed by the molding compounds which have hardened to formdisks 26 and which form secure bonds to outer edges 27, 28 of housing29. At a distance from disks 26, the housing is provided with radialconnections 30, 31 that open into channel-shaped annular spaces 32, 33which, in the manner shown, are formed by inner, ring-shaped wallsections 34, 35 which run out freely and whose edges terminate withaxial clearance before the disks. If, for example, given a verticallystanding housing, a fluid such as dialysate is introduced through lowerradial connection piece 31 into the space accommodating hollow-fiberbundle 25, the fluid tends to overflow the edge of wall 35 borderingannular groove 33, mainly in the areas near connection piece 31, so thatan unsymmetrical fluid flow, that is to say dialysate flow, develops inhousing 29.

[0043] The filter device according to the invention, explained with theaid of FIGS. 1 to 4, prevents this unsymmetrical flow, because the fluidor dialysate spreads out in annular space 21 and then, essentially withuniform circumferential distribution, enters through the inner, freeareas of inlet ports 5 into the space enclosing the hollow-fiber bundle.In the exemplary embodiment shown, annular space 21 is bounded outwardlyby the cylindrical wall of cap 15, the cap being provided with an axial,concentrically arranged intake nipple, so that the fluid spreads outwith equal pressure in annular space 21. Since an essentially equalfluid pressure occurs over the periphery of annular space 21, the intakeports formed by the free areas of inlet notches 5 can also have equalcross-sections.

[0044] In the exemplary embodiment according to FIG. 6, the fluid or thedialysate enters through radial bore holes 41 of pipe-section-shapedhousing 36 into an annular space 37 which is formed by a U-shaped ring38 whose outwardly-pointing legs are joined in a fluid-tight manner tothe housing casing. Provided in the legs of U-shaped ring 38 are boreholes 39, uniformly distributed over the circumference, through whichthe fluid introduced into annular space 37 can enter into the chambercontaining the hollow-fiber bundle.

[0045] The pipe-section-shaped housing is provided, in the area of thelower side of the annular space, with an outer, radially circumferentialflange 40 upon which the edge of a cap can be placed, in a correspondingmanner as in the case of the device described with the aid of FIGS. 1 to4, so that between the cylindrical circumferential wall of the cap andthe upper part of housing 6, an annular space is formed through whichfluid can be conducted, with equal pressure distribution, to radial boreholes 35 distributed over the periphery of the housing.

[0046]FIG. 7 shows a side view of a filter device, in the case shown, adialyzer. In this dialyzer, the connections or connection pieces usedfor connecting to the nozzles of a dialysis machine are located on oneside and have center lines parallel to one another, so that they can besealingly pressed, directly or through a suitable device, onto thenozzles of the dialysis machine.

[0047] In the filter device evident from FIG. 7 and 8, the upper andlower caps provided with the connections and connection piecesrespectively are made of parts produced separately in the injectionmolding process whose edges are butt joined in a fluid-tight manner bysuitable welded or adhesive joints to the edges of the housing whichopen out bell-shaped.

[0048] As is clear from FIG. 8, the blood chamber and the dialysatechamber surrounding hollow fibers 55 are separated by a molding compound50. At its upper edge area, the molding compound has a circumferentialgroove into which an O-ring 51 is inserted to seal off the blood chamberfrom the dialysate chamber. As FIG. 8 clearly shows, opening 53 leadinginto connection piece 52 is joined directly to the lower side of O-ring51, the annular space 54 used for the supply and removal of thedialysate extending to the O-seal, so that there is no dead space inwhich air bubbles could collect.

[0049] The function of the invention will be described using blood as anexample of a fluid that requires the removal of impurities. According tothe present invention, blood enters the first fluid flow space through afluid port formed by connection piece 12. The blood then travels throughthe first fluid path, which extends through the molding compounds 7, 50,and exits through a second fluid port. During the course of travelingthrough the first fluid flow space the blood is cleaned of impurities,said impurities diffusing into and being carried away by the dialysatein the second fluid flow space.

[0050] Clean dialysate fluid is introduced into the second fluid flowspace through an extension 16 of the second cap 14 or through fluid port52. The dialysate spreads out in annular space 21, 54 and flows throughnotches 5 into the portion of the second flow path surrounding the firstfluid flow path. Alternatively, the blood may flow through bore holes 41into annular space 37 and then through second bore holes 39 into theportion of the second flow space surrounding the first flow space. Thedialysate and the blood may flow in opposite directions (counter-currentflow), or they may flow in the same direction. As the dialysate movesthrough the portion of the second flow space surrounding the first flowspace, impurities diffuse from the blood into the dialysate and theimpurity-laden dialysate exits the device through a second fluid port.

What is claimed is:
 1. A filter device comprising a housing, a firstfluid flow path contained in said housing, a molding compound adjacentthe ends of the first fluid flow path, a first fluid port for fluidinflow and outflow from said first fluid flow path, a first cap joinedto said molding compound and the first fluid port, a second capconnected to said housing and overlapping said first cap, a second fluidflow path between said first and second caps and in a space between thehousing and the first fluid flow path, a second fluid port providingfluid inflow and outflow from the second fluid flow path, a ring havingprojections and having axial notches in fluid communication with saidsecond fluid flow path.
 2. The device of claim 1 wherein said housing isgenerally cylindrical in shape.
 3. The device of claim 2 wherein saidhousing is widened at at least one end such that the portion of thehousing joining said second cap has a diameter greater than theremainder of said housing.
 4. The device of claim 2 wherein the housinghas, near at least one end, a flange extending radially outwardly andconnected to said second cap.
 5. The device of claim 2 wherein saidmolding compound is a hardened disk.
 6. The device of claim 2 whereinthe outer margins of said projections are bound in the molding compoundsuch that portions of said notches free of molding compound are in fluidcommunication with said second fluid flow path.
 7. The device of claim 2wherein said projections are scalloped or tooth-like.
 8. The device ofclaim 2 wherein said projections have secondary projections extendingradially outwardly from said projections.
 9. The device of claim 2wherein the circumferential distance between said projections is greaterthan the circumferential width of said projections.
 10. The device ofclaim 6 wherein the cross-sectional area of said notches increases withthe increasing circumferential distance of each notch from a fluid portpositioned at a predetermined radial location.
 11. The device of claim10 wherein fluid flow through each of said notches is substantiallyequal when fluid is introduced from said fluid port.
 12. The device ofclaim 1 wherein said first fluid flow path consists of a hollow-fiberbundle.
 13. The device of claim 6 further comprising a saucer-shapedring having radial legs with bore holes therein, said legs beingconnected to the inside wall of said housing, such that said notchesopen into an annular space defined by said saucer-shaped rings.
 14. Thedevice of claim 13 wherein the saucer-shaped rings are u-shaped.
 15. Thedevice of claim 2 wherein at least one of said first and said secondfluid ports extends in an axial direction.
 16. The device of claim 2wherein at least one of said first and said second fluid ports extendsin a radial direction.
 17. The device of claim 6 wherein the ring ismade of a material which does not form a tight adhesive bond with themolding compound.
 18. The device of claim 17 wherein the ring is made ofpolypropylene.
 19. The device of claim 2 wherein the molding compound ismade of a polyurethane.
 20. The device of claim 2 wherein the first capis connected to the molding compound in a fluid-tight manner.
 21. Thedevice of claim 20 further comprising an o-ring between said first capand said molding compound.
 22. The device of claim 2 wherein said secondcap is connected to said housing in a fluid-tight manner.
 23. The deviceof claim 2 wherein the projections in said ring are bound in saidmolding compound and radial bore holes are provided in said housing,said bore holes in fluid communication with said second fluid flow path.24. The device of claim 23 further comprising a saucer-shaped ringhaving radial legs with bore holes therein, said legs being joined tothe inside wall of said housing, such that said bore holes open into anannular space defined by said saucer-shaped rings.
 25. A dialysis filtercomprising a housing, a first fluid flow path contained in said housing,a molding compound adjacent the ends of the first fluid flow path, afirst fluid port for fluid inflow and outflow from said first fluid flowpath, a first cap joined in a fluid-tight manner to said moldingcompound and the first fluid port, a second cap connected to saidhousing in a fluid tight manner and overlapping said first cap, a secondfluid flow path located between said first and second caps and furtherlocated in a space between the housing and the first fluid flow path,said housing widened at one or both ends such that the portion of thehousing connected to said second cap has a diameter greater than theremainder of said housing, a second fluid port providing fluid inflowand outflow from the second fluid flow path, a ring having projectionsand having axial notches, the margins of said projections being bound insaid molding compound such that a portion of said notches is free ofmolding compound, the portion of said notches free of molding compoundbeing in fluid communication with said second fluid flow path.
 26. Thedevice of claim 25 wherein said housing has, adjacent the widenedportion of said housing, an annular flange extending radially outwardly,said second caps being connected to said flange in a fluid-tight manner.27. The device of claim 25 wherein said projections are bound in moldingcompound and bore holes are provided in said housing, said bore holes influid communication with said second fluid flow path.
 28. The device ofclaim 25 further comprising a saucer-shaped ring having radial legs withbore holes therein, said legs being joined to the inside wall of saidhousing, such that the annular space formed by said saucer-shaped ringis in fluid communication with said second fluid flow path.
 29. Thedevice of claim 25 wherein said fluid ports are axially oriented. 30.The device of claim 25 wherein said fluid ports are radially oriented.31. The device of claim 25 wherein the cross-sectional area of the freeportions said notches increases with the increasing circumferentialdistance of each notch from a fluid port positioned at a predeterminedradial location, such that fluid flow through each of said notches issubstantially equal when fluid is introduced from said radially locatedfluid port.
 32. The device of claim 27 wherein the cross-sectional areaof the bore holes increases with the increasing circumferential distanceof each bore hole from a fluid port positioned at a predetermined radiallocation, such that fluid flow through each of the bore holes issubstantially equal when fluid is introduced from said radially locatedfluid port.
 33. The device of claim 25 wherein said first flow pathconsists of a hollow-fiber bundle.
 34. A method of filtering a fluidcomprising the step of providing a filter device comprising a housing, afirst fluid flow path contained in said housing, a molding compoundadjacent the ends of the first fluid flow path, a first fluid port forfluid inflow and outflow from said first fluid flow path, a first capjoined to said molding compound and the first fluid port, a second capconnected to said housing and overlapping said first cap, a second fluidflow path between said first and second caps and in a space between thehousing and the first fluid flow path, a second fluid port providingfluid inflow and outflow from the second fluid flow path, a ring havingprojections and having axial notches in fluid communication with saidsecond fluid flow path, and further comprising the steps of flowing afirst fluid through the first fluid flow path and flowing a second fluidthrough the second fluid flow path, impurities from said first fluiddiffusing into and said second fluid, said second fluid with saidimpurities flowing out of said second fluid flow path through saidsecond fluid port.
 35. The method of claim 34 wherein the first andsecond fluids flow in counter-current.
 36. The method of claim 34further comprising the step of positioning the filter device, for atleast a portion of the period of operation, such that gas bubbles cannotcollect in said flow paths.
 37. The method of claim 36 wherein saidfilter device is positioned vertically and said first and second fluidports attach to fluid supply and discharge lines such that gas bubblescannot collect in said flow paths.
 38. The method of claim 34 furthercomprising the steps of flowing said first fluid through said moldingcompounds and through said first fluid flow path and exiting said devicethrough said first fluid port, and flowing said second fluid into thesecond fluid flow path, said second fluid spreading out in the spacebetween said first and second caps and flowing through said axialnotches into the space between said housing and said first fluid flowpath, said second fluid flowing over said first fluid flow path, saidsecond fluid flowing through said notches into said space between saidfirst and second caps and exiting said device.
 39. The method of claim34 wherein the projections in said ring are bound in said moldingcompound and radial bore holes are provided in said housing, said boreholes in fluid communication with said second fluid flow path, thedevice further comprising a saucer-shaped ring having radial legs withbore holes therein, said legs being joined to the inside wall of saidhousing, such that said bore holes open into an annular space defined bysaid saucer-shaped rings, said second fluid flowing from the spacebetween said first and second caps through said bore holes in saidhousing into said annular space and through said bore holes in saidradial legs into the space between said housing and said first fluidflow path.